KINETICS OF NITRIC-OXIDE FORMATION BEHIND SHOCK-WAVES

The infrared radiation of nitric oxide (NO) behind a shock wave in O-2 -N-2 mixtures has been calculated by two different techniques, and com pared with recent shock-tube experiments, The first technique (model I ) utilizes the Park model. This model incorporates the vibrational rel axation of O-2 and N-2 and assumes a Boltzmann distribution of vibrati onal energy during the relaxation process. Model II uses a master equa tion solution, employing recently published state to-state vibration-t ranslation and vibration-vibration transition probabilities, Vibration -chemistry coupling is provided through the Macheret-Fridman-Rich mode l (MFR), The calculations are compared with experimental results for s hock waves in the range of 3-4 km/s, Results of the two model calculat ions are compared at speeds up to 9 km/s, for both normal shocks and b ow shocks. The two models predict nearly the same NO production rates behind all of the normal shocks, and show the prominent effect of N-2 vibrational coupling in the reaction N-2+ O --> NO + N. For high-altit ude bow shocks, where extreme vibrational nonequilibrium is present, t here are large differences in the results calculated by the Park and M FR coupling techniques.